U.S. patent number 8,859,948 [Application Number 13/221,094] was granted by the patent office on 2014-10-14 for apparatus and method for producing a component and aircraft structure component.
This patent grant is currently assigned to Airbus Operations GmbH. The grantee listed for this patent is Clemens Bockenheimer, Axel Herrmann, Pierre Zahlen, Ichwan Zuardy. Invention is credited to Clemens Bockenheimer, Axel Herrmann, Pierre Zahlen, Ichwan Zuardy.
United States Patent |
8,859,948 |
Zuardy , et al. |
October 14, 2014 |
Apparatus and method for producing a component and aircraft
structure component
Abstract
An apparatus for producing a component includes a material
storage tank for receiving a liquid material (M), a molding tool in
which a filling region to be filled with material (M) from the
material storage tank is formed, and a material supply line which
connects the material storage tank to the filling region of the
molding tool. In the region of the material supply line and/or the
filling region of the molding tool an optical fiber has been
arranged, into which at least one Fibre Bragg Grating sensor for
detecting a parameter that is characteristic of the flow of
material through the material supply line and/or the filling region
of the molding tool is integrated.
Inventors: |
Zuardy; Ichwan (Hamburg,
DE), Zahlen; Pierre (Stade, DE),
Bockenheimer; Clemens (Bremen, DE), Herrmann;
Axel (Stade, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Zuardy; Ichwan
Zahlen; Pierre
Bockenheimer; Clemens
Herrmann; Axel |
Hamburg
Stade
Bremen
Stade |
N/A
N/A
N/A
N/A |
DE
DE
DE
DE |
|
|
Assignee: |
Airbus Operations GmbH
(Hamburg, DE)
|
Family
ID: |
45566017 |
Appl.
No.: |
13/221,094 |
Filed: |
August 30, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120217382 A1 |
Aug 30, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61378434 |
Aug 31, 2010 |
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Foreign Application Priority Data
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Aug 31, 2010 [DE] |
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10 2010 035 958 |
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Current U.S.
Class: |
250/227.11 |
Current CPC
Class: |
B29C
44/1285 (20130101); B29C 70/086 (20130101); B29C
31/04 (20130101); B29C 70/865 (20130101); B29C
44/60 (20130101); B29C 70/546 (20130101); B29C
70/48 (20130101); B29L 2011/00 (20130101); Y02T
50/43 (20130101); B29L 2031/3076 (20130101); B64D
2045/0085 (20130101); Y02T 50/40 (20130101) |
Current International
Class: |
G01J
1/04 (20060101) |
Field of
Search: |
;250/237G,227.11-227.19
;385/12,13,37 ;356/32,35.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102007062111 |
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Jul 2009 |
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DE |
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2008/135559 |
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Nov 2008 |
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WO |
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Primary Examiner: Sohn; Seung C
Attorney, Agent or Firm: Carter DeLuca Farrell & Schmidt
LLP
Claims
The invention claimed is:
1. Apparatus for producing a component, comprising: a material
storage tank for receiving a liquid material, a moulding tool in
which a filling region to be filled with material from the material
storage tank is formed, a material supply line which connects the
material storage tank to the filling region of the moulding tool,
and at least one optical fibre arranged in the region of the
material supply line and/or the filling region of the moulding
tool, into which at least one Fibre Bragg Grating sensor for
detecting a parameter that is characteristic of the flow of
material through the material supply line and/or the filling region
of the moulding tool is integrated.
2. Apparatus according to claim 1, further comprising a control
unit that is adapted to control the flow of material through the
material supply line and/or the filling region of the moulding tool
in dependence on the signals output by the Fibre Bragg Grating
sensor.
3. Apparatus according to claim 1, wherein an optical fibre extends
along at least one section of the material supply line, wherein in
particular a plurality of Fibre Bragg Grating sensors for detecting
a parameter that is characteristic of the flow of material through
the material supply line are integrated into the optical fibre
which are arranged in distributed manner along the section of the
material supply line, and/or in that an optical fibre extends along
at least one section of the filling region of the moulding tool,
wherein in particular a plurality of Fibre Bragg Grating sensors
for detecting a parameter that is characteristic of the flow of
material through the filling region are integrated into the optical
fibre which are arranged in distributed manner along the section of
the filling region.
4. Apparatus according to claim 1, wherein an optical fibre
arranged in the region of the filling region of the moulding tool
is separated from the filling region by a separating device and/or
is arranged directly in the filling region.
5. Apparatus according to claim 1, wherein a receiving region for
receiving a core of the component realised in a sandwich
construction is formed in the moulding tool, the filling region of
the moulding tool extending along a surface of the receiving region
and/or through the receiving region.
6. Method for producing a component, comprising: supplying material
from a material storage tank into a filling region of a moulding
tool to be filled with the material from the material storage tank
via a material supply line, detecting a parameter that is
characteristic of the flow of material through the material supply
line and/or the filling region of the moulding tool by means of a
Fibre Bragg Grating sensor which is integrated into an optical
fibre arranged in the region of the material supply line and/or the
filling region of the moulding tool.
7. Method according to claim 6, wherein the flow of material
through the material supply line and/or the filling region of the
moulding tool is controlled by a control unit in dependence on the
signals output by the Fibre Bragg Grating sensor.
8. Method according to claim 6, wherein a parameter that is
characteristic of the flow of material through the material supply
line is detected by means of a plurality of Fibre Bragg Grating
sensors which are integrated into an optical fibre extending along
at least one section of the material supply line and in particular
are arranged in distributed manner along the section of the
material supply line, and/or in that a parameter that is
characteristic of the flow of material through the filling region
of the moulding tool is detected by means of a plurality of Fibre
Bragg Grating sensors which are integrated into an optical fibre
extending along at least one section of the filling region and in
particular are arranged in distributed manner along the section of
the filling region.
9. Method according to claim 6, wherein an optical fibre arranged
in the region of the filling region of the moulding tool is
separated from the filling region by a separating device and/or is
arranged directly in the filling region.
10. Method according to claim 6, wherein an optical fibre arranged
in the region of the filling region of the moulding tool is removed
from the moulding tool after completion of the supply of material
from the material storage tank into the filling region before the
material supplied into the filling region is cured.
11. Method according to claim 6, wherein an optical fibre arranged
directly in the filling region of the moulding tool remains in the
moulding tool after completion of the supply of material from the
material storage tank into the filling region while the material
supplied into the filling region is being cured.
12. Method according to claim 6, wherein a core of the component
realised in a sandwich construction is introduced into a receiving
region formed in the moulding tool, and material from the material
storage tank is supplied into a filling region of the moulding tool
which extends along a surface of the receiving region and/or
through the receiving region.
13. Method according to claim 6, wherein at least one Fibre Bragg
Grating sensor for detecting a parameter that is characteristic of
the structural integrity of the aircraft structure component is
integrated into at least one optical fibre.
14. Method according to claim 13, wherein an optical fibre is
integrated into a section of the aircraft structure component
consisting of a fibre-reinforced composite material.
15. Apparatus according to claim 1, further comprising at least one
optical fibre into which at least one Fibre Bragg Grating sensor
for detecting a parameter that is characteristic of the structural
integrity of the aircraft structure component is integrated.
Description
TECHNICAL FIELD
The invention relates to an apparatus and a method for production
and quality assurance of a component, in particular a
fibre-composite component. The invention further relates to an
aircraft structure component, in particular a fibre-reinforced
aircraft structure component, that is suitable for use as a
load-bearing component in an aircraft.
BACKGROUND
Efforts are being made in aircraft construction to employ
components on an increasing scale that consist completely or partly
of fibre-reinforced composite materials, for example
carbon-fibre-reinforced plastics (CFRP), as load-bearing
components. For example, DE 10 2007 062 111 A1 describes a
transverse-member structure consisting of carbon-fibre-reinforced
plastic, which serves for supporting the individual panels of an
aircraft-floor system for separating a passenger cabin from a cargo
compartment arranged below the passenger cabin. Furthermore, it is
likewise known from DE 10 2007 062 111 A1, for example, to employ
components realised in a sandwich construction, with a core and
also with top layers, applied onto the core, consisting of a
fibre-reinforced plastic material, as floor panels or ceiling
panels in an aircraft.
For the purpose of producing components from fibre-reinforced
composite materials, as a rule the reinforcing fibres are firstly
introduced into a moulding tool. Subsequently the fibres are
impregnated with the matrix material which is usually present in
liquid form. Finally, curing of the matrix material is effected by
appropriate control of temperature and/or pressure. Known methods
for producing components from fibre-reinforced composite materials
include injection methods, wherein the liquid matrix material is
injected into a closed moulding tool under elevated pressure of
over 6 bar. Furthermore, infusion methods are known, wherein the
reinforcing fibres are inserted into an open moulding tool and are
covered with a semipermeable membrane that is pervious to gases but
impervious to the matrix material. The semipermeable membrane is
covered by a gas-impervious film, so that an underpressure can be
applied between the semipermeable membrane and the gas-impervious
film and, as a result, liquid matrix material can be sucked into
the moulding tool.
Irrespective of whether an injection method or an infusion method
is employed for producing a component from a fibre-reinforced
composite material, the control of the flow of matrix material into
and through the moulding tool is of crucial importance for the
quality of the component. Therefore in the case of production of
the component by an infusion method with an open moulding tool the
flow of matrix material is ordinarily monitored by means of a CCD
camera. In the case of production of the component by an injection
method with a closed moulding tool, on the other hand, visual
monitoring of the flow of matrix material is not possible, so that
sensors such as, for example, ultrasonic sensors, line sensors
operating capacitively, temperature sensors or pressure sensors
come into operation here. As a rule, however, sensor-based
measuring principles of such a type are not capable of being
employed in real time, by reason of the fact that the sensors can
only detect changes in the corresponding physical measured
quantities associated with the actual advance of the front of
matrix material.
SUMMARY
The invention is directed towards the object of specifying an
apparatus and a process for producing a component that enable an
easy and reliable monitoring of a flow of material into and through
a moulding tool. Furthermore, the invention is directed towards the
object of making available a structural component for an aircraft,
in particular a fibre-reinforced structural component for an
aircraft, that suitable for use as a load-bearing component in an
aircraft.
This object is achieved by an apparatus with the features of claim
1, a method with the features of claim 6, and by an aircraft
structure component with the features of claim 13.
The apparatus according to the invention for producing a component
includes a material storage tank for receiving a liquid material.
The material received in the material storage tank is
preferentially a material, for example a plastic material, that is
suitable as matrix material of a fibrous composite material. For
example, the material received in the material storage tank may be
a curable resin, in particular an epoxy resin or an epoxy-amine
resin. For example, the material storage tank may be filled with an
RTM6 resin manufactured by Hexcel. The apparatus according to the
invention further includes a moulding tool in which a filling
region to be filled with material from the material storage tank is
formed. Furthermore, a material supply line is present which
connects the material storage tank to the filling region of the
moulding tool.
Merely one uninterrupted filling region to be filled with material
from the material storage tank may is formed in the moulding tool.
Alternatively, however, the moulding tool may also exhibit several
filling regions, separated from one another, to be filled with
material from the material storage tank. With such a configuration
of the moulding tool, preferentially several material supply lines
are also present which connect the individual filling regions,
separated from one another, of the moulding tool to the material
storage tank. Furthermore, an uninterrupted filling region may, of
course, also be connected to the material storage tank via several
material supply lines, for example if it is desired to fill the
filling region formed in the moulding tool as quickly as possible,
via various material inlets or from various directions, with
material from the material storage tank.
In the course of producing a component by means of the apparatus
according to the invention the liquid material is conveyed out of
the material storage tank through the material supply line into the
moulding tool and finally through the filling region of the
moulding tool, preferentially until the filling region of the
moulding tool is completely filled with the material from the
material storage tank. For the purpose of conveying the material
out of the material storage tank into the filling region of the
moulding tool, a suitable conveying device, for example a pump, may
be present. The pump may be provided to subject the liquid material
in the material storage tank to an elevated pressure of, for
example, over 6 bar. Alternatively, however, the conveying device
may also be adapted to generate an underpressure in the filling
region of the moulding tool and thereby to suck material out of the
material storage tank into the filling region of the moulding
tool.
The apparatus according to the invention can be employed for the
purpose of producing a component consisting merely of the material
from the material storage tank. In particular, the apparatus
according to the invention may, however, come into operation for
the purpose of producing a component that consists, at least in
sections, of a fibre-reinforced composite material. Production of a
component consisting, at least in sections, of a fibre-reinforced
composite material by means of the apparatus according to the
invention may be undertaken by an injection method or by an
infusion method. Furthermore, according to demand, use may be made
of an open or a closed moulding tool. Irrespective of the
configuration of the conveying device and of the moulding tool,
however, a movement of a front of the material through the material
supply line and subsequently through the filling region formed in
the moulding tool always occurs.
If the liquid material received in the material storage tank, as
mentioned above, is to find application as matrix material of a
fibre-reinforced composite material, prior to the supply of the
material from the material storage tank a fibrous material can be
introduced into the moulding tool, i.e. into the filling region
formed in the moulding tool. The reinforcing fibres can be
introduced into the filling region of the moulding tool in the form
of individual fibres designed as short fibres or continuous fibres,
as a fibrous wad or in the form of a two-dimensional or
three-dimensional fibrous fabric. The introduction of reinforcing
fibres into the filling region of the moulding tool, however, does
not alter the fact that in the course of the supply of the liquid
material from the material storage tank into the filling region of
the moulding tool a front of the liquid material moves firstly
through the material supply line and subsequently through the
filling region of the moulding tool.
The flow of the material out of the material storage tank through
the material supply line and/or the filling region of the moulding
tool constitutes an important process parameter in the course of
producing a component by means of the apparatus according to the
invention. The rate of motion of a flow front of the material out
of the material storage tank through the material supply line
and/or the filling region of the moulding tool depends, inter alia,
on the temperature, on the (temperature-dependent) viscosity of the
material and on the conveying capacity of a conveying device for
conveying the material out of the material storage tank through the
material supply line and/or the filling region of the moulding
tool. Therefore the apparatus according to the invention includes
at least one optical fibre arranged in the region of the material
supply line and/or the filling region of the moulding tool.
Integrated into this optical fibre is at least one Fibre Bragg
Grating sensor for detecting a parameter that is characteristic of
the flow of material through the material supply line and/or the
filling region of the moulding tool. The Fibre Bragg Grating sensor
is constituted by a section of the optical fibre in which the
refractive index of a fibre core varies periodically, so that,
depending on the period, light of a certain wavelength is reflected
by the Bragg grating structure. In particular, the light reflection
of the Bragg grating structure obeys the condition
.lamda..sub.B=[(n.sub.1+n.sub.2)/2]2.LAMBDA. where .lamda..sub.B is
the wavelength of the light reflected from the Bragg-grating
structure, n.sub.1 and n.sub.2 are the periodically varying
refractive indices of the fibre core, and .LAMBDA. is the period of
the refractive-index variation.
A deformation of the optical fibre in the longitudinal direction of
the fibre, which may be caused by a mechanical elongation or
compression of the fibre, but also by a change in temperature in
the environment of the fibre, results in an alteration of the
period .LAMBDA. of the Bragg grating and consequently in an
alteration of the wavelength .lamda..sub.B of the light reflected
from the Bragg-grating structure. A registration of the wavelength
.lamda..sub.B of the light reflected from the Bragg-grating
structure of the Fibre Bragg Grating sensor consequently enables a
very accurate detection of a deformation of the optical fibre in
the longitudinal direction of the fibre. If a mechanical
deformation of the optical fibre is excluded, that is to say, if
the deformation of the fibre is exclusively temperature-induced and
consequently capable of being described by the coefficient of
thermal expansion of the fibre, the evaluation of the wavelengths
.lamda..sub.B of the light reflected from the Bragg grating
structure of the Fibre Bragg Grating sensor consequently
immediately enables conclusions as regards changes of temperature
in the environment of the optical fibre.
The Fibre Bragg Grating sensor can consequently be used in the
apparatus according to the invention for producing a component for
the purpose of detecting deformations of the optical fibre in the
longitudinal direction of the fibre that are caused by changes of
temperature in the environment of the optical fibre. These changes
of temperature are, in turn, caused by the flow of the material out
of the material storage tank through the material supply line
and/or through the filling region of the moulding tool. In other
words, the Fibre Bragg Grating sensor detects a deformation of the
optical fibre in the longitudinal direction of the fibre, which is
caused by a change of temperature in the environment of the optical
fibre as a parameter characteristic of the flow of material through
the material supply line and/or through the filling region of the
moulding tool.
The Fibre Bragg Grating sensor employed in the apparatus according
to the invention is fundamentally capable of detecting even small
changes of temperature in the environment of the optical fibre very
accurately. A particularly high measurement accuracy, however, is
obtained when the material in the material storage tank has a
temperature differing from that of the moulding tool. For example,
the material in the material storage tank may be heated up to a
temperature of about 80.degree. C., whereas the material supply
line and/or the moulding tool is/are heated up to a temperature of
about 120.degree. C. It will be understood that the movement of a
front of the material out of the material storage tank through the
material supply line and/or the filling region of the moulding tool
then has the consequence of an immediate change of temperature in
the environment of the optical fibre arranged in the region of the
material supply line and/or the filling region of the moulding
tool. In particular, the change of temperature in the environment
of the optical fibre can be detected even before the front of the
material has actually passed the Fibre Bragg Grating sensor. By
means of the Fibre Bragg Grating sensor the progress of the front
of the material through the material supply line and/or the filling
region of the moulding tool can consequently be detected in real
time. The range of temperature that is capable of being detected by
means of a Fibre Bragg Grating sensor preferentially lies between
-270.degree. C. and 200.degree. C.; the measurement accuracy
preferentially amounts to .DELTA.T.ltoreq.0.5 K and the
reproducibility of the measurements is around 0.1 K.
The apparatus according to the invention for producing a component
consequently enables an easy and reliable monitoring of the flow of
material out of the material storage tank through the material
supply line and/or the filling region of the moulding tool.
According to demand, merely the flow of material through the
material supply line or the filling region of the moulding tool can
be monitored by means of a Fibre Bragg Grating sensor.
Preferentially, however, both the flow of material through the
material supply line and the flow of material through the filling
region of the moulding tool are monitored. A further advantage of
the Fibre Bragg Grating sensor employed in the apparatus according
to the invention for producing a component consists in the small
physical size of the optical fibre receiving the Fibre Bragg
Grating sensor. In principle, merely a single optical fibre with an
integrated Fibre Bragg Grating sensor or with a plurality of
integrated Fibre Bragg Grating sensors may be employed in order to
monitor the flow of material through the material supply line
and/or the filling region of the moulding tool. If desired or if
required for reasons of measurement accuracy, bundles of optical
fibres with integrated Fibre Bragg Grating sensors may, of course,
also be employed, which may be arranged along the material supply
line or integrated into the moulding tool.
The parameter detected by the Fibre Bragg Grating sensor, which is
characteristic of the flow of material through the material supply
line and/or the filling region of the moulding tool, may be
evaluated by means of a suitable evaluating unit and, if desired,
monitored manually. For example, the evaluating unit may include a
light-source for coupling light into the optical fibre, as well as
a spectrometer for detecting the wavelength of the light reflected
from the Bragg Grating structure of the Fibre Bragg Grating sensor.
From the wavelength of the light reflected from the Bragg-grating
structure of the Fibre Bragg Grating sensor the evaluating unit can
then determine the change of temperature to be measured in the
environment of the optical fibre. The apparatus according to the
invention, however, preferentially includes a control unit
integrated into the evaluating unit or formed separately, which,
for example, is realised in the form of an electronic control unit
and may be adapted to control the flow of material through the
material supply line and/or the filling region of the moulding tool
automatically in dependence on the signals output by the Fibre
Bragg Grating sensor or the evaluating unit. For example, the
control unit may be adapted to receive the signals output by the
Fibre Bragg Grating sensor or by the evaluating unit and to control
a heating device for heating the material storage tank, a heating
device for heating the moulding tool, and/or a conveying device for
conveying the material out of the material storage tank through the
material supply line and/or the filling region of the moulding tool
in dependence on the signals output by the Fibre Bragg Grating
sensor or. By appropriately controlling a heating device for
heating the material storage tank and/or a heating device for
heating the moulding tool, the viscosity of the material flowing
through the material supply line and/or the filling region of the
moulding tool and consequently the rate of flow of the material
through the material supply line and/or the filling region of the
moulding tool can be influenced. In similar manner, by
appropriately controlling a conveying device the flow-rate of the
material through the material supply line and/or the filling region
of the moulding tool can be influenced. The control unit
consequently makes it possible to react immediately to the results
of measurement provided by the Fibre Bragg Grating sensor. For
example, the control unit can compare the measured values provided
by the Fibre Bragg Grating sensor with corresponding set values,
and on the basis of a measured-value/set-value comparison of such a
type can bring influence to bear on the flow of material though the
material supply line and/or the filling region of the moulding
tool.
In the apparatus according to the invention for producing a
component, an optical fibre or an optical fibre bundle may extend
along at least one section of the material supply line. For
example, the material supply line may be wrapped around by an
optical fibre bundle. A plurality of Fibre Bragg Grating sensors
for detecting a parameter that is characteristic of the flow of
material through the material supply line may be integrated into
the optical fibre or into the optical fibre bundle. The Fibre Bragg
Grating sensors are preferentially arranged in distributed manner
along the material supply line, so that an advance of the front of
the material through the material supply line can be registered
more or less continuously.
Alternatively or additionally, an optical fibre or an optical fibre
bundle may extend along at least one section of the filling region
of the moulding tool. Particularly when the filling region of the
moulding tool or a filling-region section is of planar design, a
planar arrangement of an optical fibre bundle in the region of the
planar filling region or filling-region section also presents
itself, since this enables a surface-covering detection of the
progress of the material through the filling region. In turn, a
plurality of Fibre Bragg Grating sensors for detecting a parameter
that is characteristic of the flow of material through the filling
region may be integrated into the optical fibre or into the optical
fibre bundle. The Fibre Bragg Grating sensors are preferentially
arranged in distributed manner along the filling region, so that,
once again, an almost continuous and preferentially
surface-covering detection of the progress of the front of the
material through the filling region of the moulding tool becomes
possible.
An optical fibre arranged in the region of the filling region of
the moulding tool or an optical fibre bundle arranged in the region
of the filling region of the moulding tool may be separated from
the filling region by a separating device. The separating device
may, for example, be designed in the form of a semipermeable
membrane that is pervious to gases but impermeable to the material
from the material storage tank, or in the form of another film, for
example a gas-impervious film. If the optical fibre or the optical
fibre bundle is separated from the filling region by a separating
device, this avoids the optical fibre or the optical fibre bundle
being contaminated by the liquid material to be introduced into the
filling region of the moulding tool. The optical fibre or the
optical fibre bundle can then be re-used particularly easily and
conveniently, that is to say, it may come into operation in the
course of producing several components.
Alternatively or additionally, however, an optical fibre or an
optical fibre bundle may also be arranged directly in the filling
region of the moulding tool. With such a configuration of the
apparatus according to the invention for producing a component, the
optical fibre or the optical fibre bundle is directly flowed around
by the liquid material in the course of the supply of material from
the material storage tank into the filling region of the moulding
tool. This enables the realisation of a particularly high
measurement accuracy, wherein by reason of the small physical size
of the optical fibre the flow of material through the material
supply line and/or the filling region is not significantly
influenced or even impaired. If the optical fibre or the optical
fibre bundle is to be re-used and if the material supplied into the
filling region of the moulding tool is a curable material, after
the supply of the material into the filling region of the moulding
tool it is, however, necessary to remove the optical fibre or the
optical fibre bundle from the filling region of the moulding tool
before the liquid material supplied into the filling region of the
moulding tool is cured. Furthermore, the optical fibre or the
optical fibre bundle has to be cleaned after removal from the
filling region of the moulding tool.
In a preferred embodiment of the apparatus according to the
invention for producing a component a receiving region for
receiving a core of a sandwich component is formed in the moulding
tool. The filling region of the moulding tool may extend along a
surface of this receiving region. As a result, a core of a sandwich
component introduced into the moulding tool can be provided with a
surface layer that includes the material from the material storage
tank. If desired, the moulding tool may be configured in such a way
that a core of a sandwich component received in the moulding tool
can be provided in the region of two opposing surfaces with a
surface layer that includes the material from the material storage
tank. For this purpose the moulding tool may be provided with an
uninterrupted filling region which extends along the opposing
surfaces of the receiving region of the moulding tool which is
provided for receiving the core of the sandwich component.
Alternatively, however, the moulding tool may also be provided with
two filling regions separated from one another, which each extend
along a surface of the receiving region and are connected to the
material storage tank via a separate material supply line. A
filling region or filling-region section that is suitable for
forming a surface layer on a core of a sandwich component received
in the moulding tool is preferentially monitored by means of an
optical fibre bundle arranged in planar manner, which enables a
surface-covering detection of the progress of material through the
filling region or the filling-region section.
Furthermore, the filling region of the moulding tool may extend
through the receiving region of the moulding tool which is provided
for receiving a core of a sandwich component. With such a
configuration of the moulding tool, regions integrated into the
core of a sandwich component, in particular reinforcing regions,
can be manufactured that include the material from the material
storage tank. It will be understood that in the region of a filling
region that, for the purpose of producing a reinforcing region
integrated into the core of a sandwich component, extends through a
receiving region formed in the moulding tool an optical fibre may
also be arranged, into which a Fibre Bragg Grating sensor or a
plurality of Fibre Bragg Grating sensors for detecting a parameter
that is characteristic of the flow of material through the filling
region has/have been integrated. The flow of material through the
filling-region section extending through a receiving region formed
in the moulding tool may take place substantially perpendicular to
the flow of material through a filling-region section that is
suitable for forming a surface layer on a core of a sandwich
component received in the moulding tool.
A method according to the invention for producing a component
includes the supplying of material from a material storage tank
into a filling region of a moulding tool to be filled with the
material from the material storage tank via a material supply line.
If the method according to the invention is to be employed for the
purpose of producing a component that is fibre-reinforced at least
in sections, prior to the supply of material from the material
storage tank into the filling region of the moulding tool a fibrous
material can be introduced into the filling region of the moulding
tool. Furthermore, the production method according to the invention
includes the detecting of a parameter that is characteristic of the
flow of material through the material supply line and/or the
filling region of the moulding tool by means of a Fibre Bragg
Grating sensor which is integrated into an optical fibre arranged
in the region of the material supply line and/or the filling region
of the moulding tool.
The flow of material through the material supply line and/or the
filling region of the moulding tool can be controlled by a control
unit in dependence on the signals output by the Fibre Bragg Grating
sensor.
A parameter that is characteristic of the flow of material through
the material supply line can be detected by means of a plurality of
Fibre Bragg Grating sensors that are integrated into an optical
fibre extending along at least one section of the material supply
line and in particular that are arranged in distributed manner
along the material supply line. Additionally or alternatively, a
parameter that is characteristic of the flow of material through
the filling region of the moulding tool can be detected by means of
a plurality of Fibre Bragg Grating sensors that are integrated into
an optical fibre extending along at least one section of the
filling region and in particular that are arranged in distributed
manner along the filling region.
An optical fibre arranged in the region of the filling region of
the moulding tool may be separated from the filling region by a
separating device. Additionally or alternatively, an optical fibre
arranged in the region of the filling region of the moulding tool
may be arranged directly in the filling region.
After completion of the supply of material from the material
storage tank into the filling region an optical fibre arranged in
the region of the filling region of the moulding tool may be
removed from the moulding tool before the material supplied into
the filling region is cured. This applies both to optical fibres
that are separated from the filling region by a separating device
and to optical fibres that are arranged directly in the filling
region.
Alternatively, however, after completion of the supply of material
from the material storage tank into the filling region it is also
conceivable to leave in the moulding tool an optical fibre arranged
directly in the filling region of the moulding tool while the
material supplied into the filling region is being cured. As a
result, a component with an optical fibre integrated into the
component, that is to say, a component with a Fibre Bragg Grating
sensor integrated into the component, can be produced.
If the process according to the invention is to be employed for the
purpose of producing a sandwich component, a core of the sandwich
component can be introduced into a receiving region formed in the
moulding tool. The material from the material storage tank can be
supplied into a filling region of the moulding tool which extends
along a surface of this receiving region. As a result, the core of
the sandwich component can be provided with a surface layer that
includes the material from the material storage tank. Additionally
or alternatively, the material from the material storage tank can
also be supplied into a filling region of the moulding tool which
extends through the receiving region into which the core of the
sandwich component is introduced. As a result, the core of the
sandwich component is provided with regions integrated into the
core that contain the material from the material storage tank.
An aircraft structure component according to the invention includes
at least one optical fibre into which at least one Fibre Bragg
Grating sensor for detecting a parameter that is characteristic of
the structural integrity of the structural component for an
aircraft is integrated. By way of parameter that is characteristic
of the structural integrity of the aircraft structure component,
the Fibre Bragg Grating sensor preferentially detects, as
elucidated above, a deformation of the optical fibre in the
longitudinal direction of the fibre, from which conclusions as
regards a mechanical or temperature-induced deformation of the
component are possible. A component of such a type can be employed
advantageously in particular when the structural integrity of the
component is particularly important. The aircraft structure
component according to the invention is consequently also suitable
as a safety-relevant component in aircraft construction.
The optical fibre is preferentially integrated into a section of
the aircraft structure component consisting of a fibre-reinforced
composite material. For example, the optical fibre may be
integrated into a section of an aircraft structure component
realised in a sandwich construction, consisting of a
fibre-reinforced composite material.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention will now be elucidated in
more detail on the basis of the appended schematic drawings, in
which
FIG. 1 shows an apparatus for producing a component;
FIG. 2 shows an optical fibre employed in the apparatus according
to FIG. 1 with an integrated Fibre Bragg Grating sensor; and
FIG. 3 shows an aircraft structure component that has been produced
by means of an apparatus according to FIG. 1.
DETAILED DESCRIPTION
FIG. 1 shows an apparatus 10 for producing a component 12
illustrated in FIG. 3. In the embodiment described here, the
component 12 has been provided for use as a structural component
for an aircraft, realised in a sandwich construction, and includes
a core 14 consisting of a foam material and also superficial top
layers 16, 18 consisting of a fibre-reinforced composite material.
Furthermore, reinforcing region 17, 19 consisting of a
fibre-reinforced composite material are integrated into the core 14
of the component. The apparatus 10 may, however, also come into
operation for the purpose of producing a differently constructed
component. For example, the apparatus 10 may be used for producing
a component that is constructed merely in one phase and, for
example, that consists of a curable plastic material.
The apparatus 10 includes a material storage tank 20 in which a
liquid material M is received. For example, the material storage
tank 20 may be filled with a curable resin such as, for example, an
epoxy resin or an epoxy-amine resin. The material M received in the
material storage tank 20 is in the liquid state. By means of a
first heating appliance 22 the material storage tank 20 or the
material M received in the material storage tank 20 can be heated
up to a desired material. In the case of the processing of epoxy
resin or epoxy-amine resin, the material storage tank can be heated
up by means of the first heating appliance 22, for example to a
temperature of about 80.degree. C.
Furthermore, the apparatus 10 includes a moulding tool 24. In the
moulding tool 24 a receiving region 26 for receiving the core 14 of
the component 12 realised in a sandwich construction is formed.
Furthermore, the moulding tool 24 includes a filling region 28 into
which a reinforcing material 30 designed in the form of a fibrous
fabric is introduced. By way of reinforcing material 30, arbitrary
fibres that are suitable for producing fibre-reinforced composite
materials may come into operation. Preferentially, however, the
reinforcing material 30 consists of carbon fibres. The core 14
inserted into the receiving region 26 of the moulding tool 24
consists, for example, of a closed-cell polymethacrylimide
foam.
The filling region 28 formed in the moulding tool 24 includes two
sections 28a, 28b which extend in planar manner along two opposing
surfaces 32, 34 of the receiving region 26. By supply of material M
from the material storage tank 20 into filling-region sections 28a,
28b, the superficial top layers 16, 18 of the component 12 covering
the sandwich-component core 14 along two opposing surfaces can
consequently be generated from a fibre-reinforced composite
material, for example from a carbon-fibre-reinforced plastic
material. Furthermore, the filling region 28 exhibits two sections
28c, 28d which extend through the receiving region 26 and
consequently through the core 14 of the sandwich component 12
received in the receiving region 26. A reinforcing material 30
designed in the form, for example, of carbon fibres is introduced
into sections 28c, 28d of the filling region 28, so that by virtue
of the supply of material M from the material storage tank 20 into
filling-region sections 28c, 28d the reinforcing regions 17, 19
integrated into the core 14 of the sandwich component 12 can be
generated from carbon-fibre-reinforced plastic.
The filling region 28 of the moulding tool 24 is connected to the
material storage tank 20 via a material supply line 38.
Furthermore, the filling region 28 formed in the moulding tool 24
is connected via a line 40 to a conveying device 42 designed in the
form of a pump. In the embodiment of the apparatus 10 illustrated
in FIG. 1 the conveying device 42 serves to generate an
underpressure in the filling region 28 of the moulding tool 24 and
thereby to convey material M out of the material storage tank 20
into the filling region 28 of the moulding tool 24. With a
configuration of such a type, the material storage tank 20 does not
have to be subjected to elevated pressure. Alternatively, however,
an arrangement is also conceivable in which, by virtue of the
generation of an elevated pressure in the material storage tank 20
of, for example, up to 6 bar, the material M from the material
storage tank 20 is conveyed out of the material storage tank 20
into the material supply line 38 and finally into the filling
region 28 of the moulding tool 24.
In the region of their surfaces facing away from the receiving
region 26 filling-region sections 28a, 28b of the moulding tool 24
are delimited by a semipermeable membrane 44 that is pervious to
gases but impervious to the material M from the material storage
tank 20. The semipermeable membrane 44 is, in turn, covered with a
gas-pervious film 46. The line 40 connected to the conveying device
42 is linked to the interspace formed between the semipermeable
membrane 44 and the film 46. A configuration of such a type makes
it possible to generate in the filling region 28 of the moulding
tool 24 the underpressure required for conveying the material M out
of the material storage tank 20 into the filling region 28, and at
the same time to prevent material M from the material storage tank
20 from being sucked out of the filling region 28 into the line
40.
The material supply line 38 connecting the material storage tank 20
to the filling region 28 of the moulding tool 24 is wrapped around
with a first optical fibre bundle 48a. An individual fibre 48 of an
optical fibre bundle of such a type is illustrated in detail in
FIG. 2. A plurality of Fibre Bragg Grating sensors 50 which are
arranged in distributed manner along the material supply line 38
are integrated into the individual fibres 48 of the first optical
fibre bundle 48a. Each of the fibre Bragg-grating sensors 50 is
constituted by a section of the optical fibre 48 in which the
refractive index n.sub.1, n.sub.2 of a fibre core varies
periodically, so that light of a certain wavelength .lamda..sub.B
is reflected by the Bragg Grating structure in dependence on the
period .LAMBDA..
A second optical fibre bundle 48b is arranged in the region of
filling-region section 28a, the second optical fibre bundle 48b
extending two-dimensionally, i.e. in planar manner, along
filling-region section 28a. A plurality of Fibre Bragg Grating
sensors 50 which are arranged in planar distributed manner along
filling-region section 28a are also integrated into the second
optical fibre bundle 48b. In similar manner, a third optical fibre
bundle 48c is positioned in planar manner in the region of
filling-region section 28b. Just like the second optical fibre
bundle 48b, the third optical fibre bundle 48c also includes a
plurality of Fibre Bragg Grating sensors 50 which are arranged in
planar distributed manner along filling-region section 28b.
However, unlike the third optical fibre bundle 48c which is
arranged directly in filling-region section 28b, the second optical
fibre bundle 48b is separated from filling-region section 28a by
the separating membrane 44. The semipermeable membrane 44
consequently constitutes a separating device which separates the
second optical fibre bundle 48b from filling-region section 28a and
consequently also from the material M from the material storage
tank 20 to be supplied into filling-region section 28a. Lastly,
fourth and fifth optical fibre bundles 48d, 48e extend through
filling-region sections 28c, 28d. Fibre Bragg Grating sensors 50
which are arranged in distributed manner along filling-region
sections 28c, 28d are also integrated into the fourth and fifth
optical fibre bundles 48d, 48e.
Finally, the apparatus 10 includes a second heating appliance 52
which in operation of the apparatus 10 serves to heat up the
moulding tool 24 to a desired temperature. In the course of
producing the sandwich component 12 illustrated in FIG. 3, with a
core 14 consisting of a polymethacrylimide foam and with
superficial top layers 16, 18 consisting of carbon-fibre-reinforced
plastic, the moulding tool 24 may be heated to a temperature of
about 120.degree. C. in the course of the supply of material M from
the material storage tank 20 into the moulding tool 24. When the
filling region 28 of the moulding tool 24 is completely filled with
material M from the material storage tank 20, the second heating
appliance 52 can of course also be utilised for heating up the
moulding tool 24 to a temperature that enables a curing of the
material M introduced into the filling region 28 of the moulding
tool 24. For example, a curing temperature of 180.degree. C. is
possible. The second heating appliance 52 may be designed in the
form of an oven surrounding the moulding tool 24.
In operation of the apparatus 10, by means of the conveying device
42 an underpressure is generated in the filling region 28 of the
moulding tool 24. As a result, material M is sucked out of the
material storage tank 20 into the filling region 28 of the moulding
tool 24, and the reinforcing fibres 30 arranged in the filling
region 28 are impregnated with the material from the material
storage tank 20. The flow of material through the material supply
line 28 and the individual sections 28a, 28b, 28c, 28d of the
filling region 28, i.e. the movement of a flow front F of the
material M through the material supply line 38 and the sections
28a, 28b, 28c, 29d of the filling region 28, is monitored by means
of the Fibre Bragg Grating sensors 50 integrated into the optical
fibre bundles 48a, 48b, 48c, 48d, 48e (see FIG. 2). In particular,
the Fibre Bragg Grating sensors 50 enable a virtually continuous
monitoring of the progress of the flow front F of the material M
from the material storage tank 20 through the material supply line
38 and the individual sections 28a, 28b, 28c, 28d of the filling
region 28 formed in the moulding tool 24.
In particular, an evaluating unit 54, which includes a
light-source, not illustrated in any detail in the Figures, for
coupling light into the optical fibre bundles 48a, 48b, 48c, 48d,
48e and also a spectrometer, likewise not shown, for detecting the
wavelength .lamda..sub.B of the light reflected from the Bragg
Grating structure of the Fibre Bragg Grating sensors 50, ascertains
from the wavelengths .lamda..sub.B of the light reflected from the
Bragg Grating structures of the Fibre Bragg Grating sensors 50 the
change of temperature in the environment of the respective Fibre
Bragg Grating sensors 50. The movement of the flow front F of the
material M exhibiting a temperature of about 80.degree. C. out of
the material storage tank 20 through the material supply line 38
and the filling region 28 of the moulding tool 24 which is heated
up to a temperature of about 120.degree. C. can consequently be
detected and retraced by the Fibre Bragg Grating sensors 50
distributed in planar manner along the material supply line 38 and
along filling-region sections 28a, 28b, 28c, 28d consequently
virtually continuously and almost in surface-covering manner in
real time. By reason of the small physical volume of the optical
fibre bundles 48a, 48b, 48c, 48d, 48e, the flow of material through
the material supply line 38 or through the filling region 28 of the
moulding tool 24 is not impaired significantly, even when the
optical fibre bundles 48a, 48b, 48c, 48d, 48e are directly
integrated into the material supply line 38 or into the filling
region 28 of the moulding tool.
The signals output by the Fibre Bragg Grating sensors 50 or by the
evaluating unit 54 are supplied to a control unit 56. The control
unit 56 is realised in the form of an electrical control unit. In
dependence on the signals supplied to it by the Fibre Bragg Grating
sensors 50 or by the evaluating unit 54, the control unit 56
controls the operation of the first heating appliance 22 for
heating the material storage tank 20, the operation of the second
heating appliance 52 for heating the moulding tool 24, and also the
conveying device 42 for conveying the material M out of the
material storage tank 20 into the filling region 28 of the moulding
tool 24. In other words, the control unit 56 is capable of
influencing the movement of the flow front F of the material M out
of the material storage tank 20 through the material supply line 38
and the filling region 28 of the moulding tool 24 in dependence on
the signals output by the Fibre Bragg Grating sensors 50 or the
evaluating unit 54. For this purpose the control unit 56 may, for
example, compare the rate of motion of the flow front F of the
material M out of the material storage tank 20 through the material
supply line 38 and the filling region 28 of the moulding tool 24
with corresponding set values saved in a memory of the control unit
56.
After completion of the supply of material from the material
storage tank 20 into the filling region 28 of the moulding tool 24,
the third optical fibre bundle 48c arranged directly in
filling-region section 28b remains in the moulding tool 24 also
during the following curing step. This also applies to the fourth
and fifth optical fibre bundles 48d, 48e. The sandwich component 12
illustrated in FIG. 3 consequently includes a superficial top layer
18 and also reinforcing regions 17, 19, into each of which an
optical fibre bundle 48c, 48d, 48e with corresponding Fibre Bragg
Grating sensors 50 is integrated, respectively. The second optical
fibre bundle 48b employed for monitoring filling-region section
28a, on the other hand, is removed from the moulding tool 24 prior
to the curing of the material introduced into filling-region
section 28a and can be used in the course of producing a further
component. By virtue of the arrangement of the second optical fibre
bundle 48b between the semipermeable membrane 44 and the film 46,
i.e. outside filling-region section 28a, a contamination of a
second optical fibre bundle 48a by the material M introduced into
filling-region section 28b is prevented.
The optical fibre bundles 48c, 48d, 48e, with the corresponding
Fibre Bragg Grating sensors 50, integrated into the sandwich
component 12 can be used for the purpose of monitoring the
structural integrity of the sandwich component 12. In particular,
the detection of a variation in a wavelength .lamda..sub.B of the
light reflected from the Bragg Grating structure of the Fibre Bragg
Grating sensors 50 enables conclusions as regards a deformation of
the optical fibre bundles 48b, 48d, 48e in the longitudinal
direction of the fibre bundles 48b, 48d, 48e caused by a mechanical
stressing of the component 12.
* * * * *